Bioaccessibility and health risk of arsenic, mercury and other metals in urban street dusts from a mega-city, Nanjing, China

The oral bioaccessibility and the human health risks of As, Hg and other metals (Cu, Pb, Zn, Ni, Co, Cd, Cr, Mn, V and Fe) in urban street dusts from different land use districts in Nanjing (a mega-city), China were investigated. Both the total contents and the oral bioaccessibility estimated by the Simple Bioaccessibility Extraction Test (SBET) of the studied elements varied with street dusts from different land use districts. Cd, Zn, Mn, Pb, Hg and As showed high bioaccessibility. SBET-extractable contents of elements were significantly correlated with their total contents and the dust properties (pH, organic matter contents). The carcinogenic risk probability for As and Cr to children and adults were under the acceptable level (<1 × 10⁻⁴). Hazard Quotient values for single elements and Hazard Index values for all studied elements suggested potential non-carcinogenic health risk to children, but not to adults.     

Livelihood Security, Vulnerability and Resilience: A Historical Analysis of Chibuene, Southern Mozambique

A sustainable livelihood framework is used to analyse livelihood security, vulnerability and resilience in the village of Chibuene, Vilanculos, southern Mozambique from a historical and contemporary perspective. Interviews, assessments, archaeology, palaeoecology and written sources are used to address tangible and intangible aspects of livelihood security. The analysis shows that livelihood strategies for building resilience, diversification of resource use, social networks and trade, have long historical continuities. Vulnerability is contingent on historical processes as long-term socio-environmental insecurity and resultant biodiversity loss. These contingencies affect the social capacity to cope with vulnerability in the present. The study concludes that contingency and the extent and strength of social networks should be added as a factor in livelihood assessments. Furthermore, policies for mitigating vulnerability must build on the reality of environmental insecurity, and strengthen local structures that diversify and spread risk.     

Silent water: a brief examination of the marine fisheries crisis

This paper is an attempt to synthesize and briefly examine the causes of the marine fisheries crisis, and to speculate about future initiatives. Ultimately, the human appetite is at the root of the marine fisheries crisis. But religion, technology, population pressure, science and our economic systems have provided vehicles for human appetite and thus contributed to overfishing. These various topics are further discussed in the context of the potential restoration of marine fisheries populations. All titles with gratitude to The Talking Heads. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.     

灾害史研究中的年代换算及其软件

“灾害史中的年代换算（TCHD）”软件是进行年代换算的专用软件。本文研究了几种主要历法的年代换算的具体算法．介绍了该软件的结构，流程和功能．TCHD软件使灾害学和历史学等领域的研究人员摆脱了传统的朔闰表式的历法对照和检索方式，并成为灾害史工作计算机化的一部分。     

An equation of motion for particles of finite Reynolds number and size

In order to simulate the motion of bubbles, drops, and particles, it is often important to consider finite Reynolds number effects on drag, lift, torque, and history force. Herein, an equation of motion is developed for spherical particles with a no-slip surface based on theoretical analysis, experimental data, and surface-resolved simulations. The equation of motion is then extended to account for finite particle size. This extension is critical for particles which will have a size significantly larger than the grid cell size, particularly important for bubbles, and low-density particles. The extension to finite particle size is accomplished through spatial-averaging (both volume-based and surface-based) of the continuous flow properties. This averaging is consistent with the Faxen limit for solid spheres at small Reynolds numbers and added mass and fluid stress forces at inviscid limits. The finite Re _p corrections are shown to have good agreements with experiments and resolved-surface simulations. The finite size corrections are generally fourth-order accurate and an order of magnitude more accurate than point-force expressions (which neglect quadratic and higher spatial gradients) for particles with size on the order of the gradient length-scales. However, further work is needed for more quantitative assessment of the truncation terms and the overall model robustness and accuracy in complex flows.     

The town and country planning act 1947

The 1947 Town & Country Planning Act is regarded as the statutory foundation of physical planning in post‐war Britain. This paper looks at the Act in context and assesses its effectiveness from the vantage point of forty years since its implementation.     

A moving target: planning Britain's inner cities

The authors look at Britain's post‐war response to the challenge of the Inner Cities and attempts to account for this response's more obvious failings. The paper considers the challenge facing the planners and considers the nature of their response, concluding that the future of planning as a weapon in the armoury of public policy is assured.     

Estimation of daily intake of potentially toxic elements from urban street dust and the role of oral bioaccessibility testing

The pseudo-total and oral bioaccessible concentration of six potentially toxic elements (PTEs) in urban street dust was investigated. Typical pseudo-total concentrations across the sampling sites ranged from 4.4 to 8.6 mg kg⁻¹ for As, 0.2-3.6 mg kg⁻¹ for Cd, 25-217 mg kg⁻¹ for Cu, 14-46 mg kg⁻¹ for Ni, 70-4261 mg kg⁻¹ for Pb, and, 111-652 mg kg⁻¹ for Zn. This data compared favourably with other urban street dust samples collected and analysed in a variety of cities globally; the exception was the high level of Pb determined in a specific sample in this study. The oral bioaccessibility of PTEs in street dust is also assessed using in vitro gastrointestinal extraction (Unified Bioaccessibility Method, UBM). Based on a worst case scenario the oral bioaccessibility data estimated that Cd and Zn had the highest % bioaccessible fractions (median >45%) while the other PTEs i.e. As, Cu, Ni and Pb had lower % bioaccessible fractions (median <35%). The pseudo-total and bioaccessible concentrations of PTEs in the samples has been compared to estimated tolerable daily intake values based on unintentional soil/dust consumption. Cadmium, Cu and Ni are well within the oral tolerable daily intake rates. With respect to As and Pb, only the latter exceeds the TDI_oral if we model ingestion rate based on atmospheric ‘dustiness’ rather than the US EPA (2008) unintentional soil/dust consumption rate of 100 mg d⁻¹. We consider it unlikely that even a child with pica tendencies would ingest as much as 100 mg soil/dust during a daily visit to the city centre, and in particular to the sites with elevated Pb concentrations observed in this study.